Seminar, day two
The facilitator handed out the results in the morning. By the lunch break, everyone is talking about them.
"Oh, I'm an INFJ, so it makes sense I'm exhausted after the group workshops." Someone nods. "Yeah, honestly, it shows." Another: "I'm an ENTP, so, you know, I'll argue with everything, sorry in advance." Laughter. A third explains that he's an ISTJ and can't work in a mess, and his deskmate of three years lets out "ah, that explains everything."
There's something deeply reassuring about this scene. Four letters, and suddenly you have an explanation. An explanation that even clears you: it's not a flaw, it's a type.
And let's be honest: when you read your description, you recognized yourself. Not vaguely, precisely. There were sentences that seemed written while looking straight at you. It wasn't dumb, it wasn't empty, it was unsettling in its accuracy. You even sent the link to three people.
So no, you weren't naive.
And yet.
Retake the test in five weeks. There's a good chance you won't be the same person.
Let's give the MBTI its due
Before dismantling anything, we have to say what the MBTI genuinely brought. This isn't politeness: it's true.
It normalized differences. Before it, a colleague who needed silence to work was "weird." Another who decided quickly was "impulsive." The MBTI introduced a simple, liberating idea: these differences aren't flaws, they're ways of functioning. Millions of people stopped believing themselves broken thanks to that. That's not nothing.
It gave people vocabulary. It let teams that didn't understand each other put words to a friction. "You need to structure everything before starting, I need to start in order to understand." That conversation, many would never have had it without a tool to open it.
It made personality psychology accessible. It was a dry field, full of tables and coefficients. The MBTI made it readable, shareable, fun.
And, let's admit it, it's pleasant. It gives you an identity, a community, a badge. There are INFJ forums, ENTP memes, people who bond over four letters. That's not ridiculous. It's human.
That's not where the problem is.
The problem is what it measures.
Problem #1: the test doesn't give the same result twice
Here's the fact, and it's simple.
A significant share of people get a different type when they retake the test a few weeks later. Not a nuance, not a detail: a letter that changes, sometimes two. You were ENTJ, and here you are ENTP.
Take a second to measure what that means.
If an instrument gives you a different result depending on the day you use it, it's not an instrument. It's a scale that reads 154 lbs on Monday and 181 lbs on Thursday. You wouldn't say "interesting, my weight has a complex nature." You'd say the scale is broken. And you'd be right.
So why does it happen? It's not because people change. It's because the MBTI forces categories where there's a continuum.
It sorts you introvert or extravert. Two boxes, one border. But reality doesn't work like that: extraversion is a slider, with every position in between. And above all, this is the crucial point, most people are in the middle. Neither clearly on one side nor clearly on the other. Somewhere between the two, like the majority of humanity on most traits.
Now if you're in the middle, you're sitting on the border. On a day you're tired, you answer slightly more "I." On a day you're coming off a good weekend, you answer slightly more "E." The slider itself has moved only two millimeters. But the type has flipped entirely. You change box, description, community, Instagram bio, over a tiny gap.
The image is this. Imagine we sort people into "tall" and "short," with a threshold at 5'9".
Someone who's 5'8.9" is "short." Someone who's 5'9.1" is "tall." These two people are, for all practical purposes, exactly the same height. They resemble each other infinitely more than they resemble, respectively, a 5'1" person and a 6'6" person, who are nonetheless in their box. And if you remeasure them with shoes on, or in the morning rather than the evening, they change category.
That's exactly what the MBTI does. Sixteen boxes, four arbitrary borders, and millions of people sitting astride a line. If that's you, I've given that flip a whole article.
And if you want the full verdict, criterion by criterion — reliability, validity, predictive power — I run the 16 personalities test past all three here.
Problem #2: "but I recognized myself"
That's the immediate objection, and it's legitimate. Because it's true: you recognized yourself. It wasn't a vague impression, it was sharp.
So we have to talk about the Barnum effect.
The Barnum effect is our tendency to recognize ourselves in descriptions general enough, and flattering enough, to apply to almost anyone. It's the engine of astrology, and it works with fearsome efficiency. We don't read these descriptions neutrally: we actively go looking for the memories that confirm them. "You need to be liked, but you can also be critical of yourself," and there you are, thinking back to that time when, indeed.
The classic experiment is this. Students take a questionnaire, then receive their personalized profile. They're asked to rate the accuracy of the description. The ratings are excellent: they find themselves remarkably well described.
In reality, everyone received the same text.
The same paragraph, handed to all, and each saw their intimate portrait in it.
Now look at MBTI descriptions with that eye. Notice something: they're almost all positive. There's no "unpleasant" type. No "unreliable" type. No "mediocre" type. Every type is gifted, in its own way, with its unique strengths and its pretty flaws, the kind you can mention in a job interview. The perfectionist. The too-sensitive. The too-honest.
So ask yourself this question, gently, without aggression:
A description no one can be displeased by, does it really describe anyone?
A portrait that flatters everyone distinguishes no one.
What the Big Five does instead
I'm not going to say "it's better." I'm going to say what changes, concretely.
1. It measures degrees, not categories.
You're not "an introvert." You're at 34 out of 100 on extraversion. Decisive nuance: there's no border to cross. So no possible flip. If one day you answer a bit more limply, you go from 34 to 37. You don't become someone else. You move slightly on a scale, which is exactly what reality does.
2. It's stable.
Retake it in six months: your scores will barely budge. Not by magic, but by construction. It measures a position on a scale, not membership of a box. There's nothing to flip.
3. It places you relative to others.
This may be the most useful difference, and it's rarely mentioned. "34 out of 100 on extraversion" means something precise: about two-thirds of people are more extraverted than you. That's information. You know where you are in the population.
"INFJ" tells you nothing comparative. It tells you which box you fell into, not where you stand.
4. And a deeper difference, the one that really counts.
The Big Five wasn't invented. It was discovered.
It didn't come out of some author's theory who imagined how the human mind is organized. It came out of statistical analysis of language. The method: take all the words humans use to describe themselves, talkative, suspicious, orderly, anxious, curious, warm, thousands of adjectives, across several languages, and simply look at which ones go together. Does someone called "talkative" also get called "energetic"? Does someone called "orderly" also get called "punctual"?
Five groups of words appeared. Systematically. Without anyone deciding them in advance.
That's a fundamental difference in method, and it explains all the rest.
That said, let's be clear about what the Big Five doesn't do, because you have the right to know before doing anything:
It doesn't predict your future. It doesn't tell you which job to choose. It doesn't replace a professional if something's wrong. It gives you no community, no badge, no bio.
It describes tendencies. Not a destiny.
So why is the MBTI everywhere?
That's the logical question, and it deserves a frank answer.
Because it's pleasant, memorable, communal, and sellable.
Four letters are instantly memorized. They're shared, they're compared, they go in a bio. They create tribes. They spawn memes, videos, T-shirts, dating apps. They let you say "ah, we're compatible." There's an entire economy built on this, and a corporate-training industry that's been selling workshops for decades.
"34 out of 100 on extraversion" doesn't go on a T-shirt. It has no community. It doesn't make good party conversation.
The MBTI won because it's enjoyable, not because it's accurate.
Those are two different things, and nothing obliges reality to be entertaining.
Where you actually stand
If you want to know not which box you fall into, but where you stand, on the five sliders, and relative to others, the test is here. It takes ten minutes.
You weren't foolish
Come back for a second to the seminar scene.
If you recognized yourself in your type, you weren't gullible. You recognized something true about yourself. That fatigue after meetings, that need to understand before acting, that reflex to push back: all of it exists. You didn't invent it, and the MBTI didn't plant it.
It's simply that the tool couldn't tell you how much, or compared to whom. It gave you an accurate word and a false measurement.
You're not four letters.
You're five sliders, and the sliders don't move from one test to the next.